A developer post on the Blizzard Entertainment forums announces that the 7.3 patch for World of Warcraft is now up and running on the Public Test Realm, and provides an overview of what that patch is all about. In this latest update players will take the fight straight to the Burning Legion's home planet – Argus, where they'll face hordes of demons and some environmental nastiness. Here's an excerpt:

Most (but not all) of the new stuff in 7.3 takes place on Argus—and as you might expect, this is hostile territory. Demons patrol every crag of Argus’s shattered surface, and sometimes it seems as if the planet itself is out to get you. This will be a very story-driven update, but we’re also designing areas with sandbox elements intended to be enjoyed even after you complete the main quest, with gameplay and challenges on the planet’s surface reminiscent of past endgame areas such as the Molten Front, the Isle of Thunder, and the Timeless Isle.

One of the first things you’ll encounter to help you navigate the Legion’s home turf is the Vindicaar: a vessel that will serve as your mobile base of operations—and one of your few safe havens—on Argus. Aside from giving you direct access to a number of 7.3’s new features, the Vindicaar will also be your primary method of transport behind enemy lines. Argus is a no-fly zone, similar to the Isle of Thunder, so to help make sure it’s still easy to get around, the Vindicaar will give you access to an extensive network of teleportation hubs (similar to flight paths, but without the travel time).

There are three main areas to explore on the planet, the first of which is available for testing on the PTR today!

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Other major content that’s contained in Patch 7.3 but not yet complete in this build includes:

Further chapters of the Argus storyline, including many cinematic story moments

New World Quests

Professions updates, including epic gems

The Netherlight Crucible, which allows you to upgrade your Artifact to unlock a new way to customize your Relics

New dungeon: Seat of the Triumvirate

New raid: Antorus, the Burning Throne (though as with other Legion raids, it won’t be released immediately with 7.3)

Invasion Points, a new type of replayable content that let you fight the Legion on multiple different worlds